The heart of a computer is a magnetic disk drive which typically includes a rotating disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected circular tracks on the rotating disk. When the slider rides on the air bearing, the write and read heads are employed for writing magnetic impressions to, and reading magnetic signal fields from, the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
The hard disk drive (HDD) is an indispensable device in applications that require the recording of large amounts of information on computers or consumer electronics. The rapid increase in the volume of data handled by computers has seen a rising demand for an increase in the capacity of HDDs as an auxiliary or primary storage device. Moreover, with the increased use of HDDs in domestic electrical appliances, there is a strong demand for enhanced capacity and reduced size in HDDs.
In typical systems, the magnetic recording medium used in HDDs comprises a plurality of perpendicular magnetic layers having different anisotropic magnetic fields Hk. This Exchange-Coupled Composite (ECC) structure may mitigate loss of recorded magnetization state due to noise in the medium, and has been employed in this manner in IEEE Trans. Magn., vol. 41, p. 537 (2005) and IEEE Trans. Magn., vol. 45, p. 799 (2009).
A CoCrPt alloy thin film was fabricated having various compositions and the anisotropic magnetic field Hk of the films was measured. Experimental results show that CoCrPt alloy thin films have a maximum Hk magnitude of 22 kOe. Weaker anisotropic magnetic fields destabilize magnetization in the direction perpendicular to the film surface. Thus, by only using a CoCrPt alloy, it becomes increasingly difficult to increase the difference in the anisotropic magnetic field Hk between the magnetic layers forming the magnetic recording layer. Generally, a large gain is obtained for a larger difference in the anisotropic magnetic field Hk between the magnetic layers which are combined in the ECC medium. When the medium is fabricated from only CoCrPt alloy as is typical in the art, there are constraints on the obtainable difference in anisotropic magnetic field between magnetic layers. Therefore, there is a need for developing a system and method for increasing the storage capacity of HDDs while overcoming the limitations of conventional media.